<div>
  <h2>基础用法</h2>
  <el-cascader options="options" on-change="onChange(value)"></el-cascader>
  <h2>尺寸	medium / small / mini</h2>
  <el-cascader options="options" on-change="onChange(value)" size="medium"></el-cascader>
  <el-cascader options="options" on-change="onChange(value)" size="small"></el-cascader>
  <el-cascader options="options" on-change="onChange(value)" size="mini"></el-cascader>
</div>